I have been looking trough the bug database and almost certainly found a
previous report of the same fault:
#360897 <mailto:360897@bugs.debian.org>sparc64 tftpboot kernel driver
failure during Gigaswift ethernet (aka cassini) detection.
This bug is listed in "installation-reports", Outstanding bugs -- Normal
bugs; Unclassified.

Same SunFire v440 and same Cassini network cards, same kernel Oops.
///Per